A water clarification system can be an oil-water separator used to separate contaminants from water. The water is typically rain runoff from a parking lot. The contaminants are typically oil, sludge and gravel. The separator may be buried in the ground. In operation, a mixture of the water and the contaminants enters the separator. The water exits the separator, while the contaminants are retained by and in the separator. The contaminants may be manually removed from the separator by way of manholes located along the top of the separator.